Mountains of water ice tower thousands of meters over fields of frozen nitrogen and methane. Glaciers etched with channels hint at heat bubbling up from below. A patchwork of new and old terrains — some laid down in the last 10 million years, some as old as the planet itself — blanket the ground. And what appear to be two ice volcanoes punch through the terrain.

Tiny, far-flung Pluto is about to have a visitor — at least for a few hours.

On July 14, NASA’s New Horizons spacecraft will reach the dwarf planet and try to learn all it can about Pluto and its five known moons. Then the probe will leave Pluto behind, vanishing into the frigid darkness beyond the planets.

Gas bubbles effervesce from a mound of muck on the seafloor in a deep submarine canyon off the west coast of Canada. Microbes beneath the sediment belch the bubbles after feasting on the ancient remains of algae, sea critters and their poop: a primordial stew that’s been simmering since long before humans walked the Earth.

Suppose there was a fourth little pig. This one was a physicist. Unlike his brother the engineer, who built a house out of tried-and-true bricks, the physicist pig chose a building material by doing calculations based on fundamental principles. He settled on a substance made from silicon and oxygen, an abundant material with high bond strength and the aesthetic bonus of transparency. It was...

What Martin Nweeia noticed first when he encountered narwhals, he says, was the sound. In May 2000, as spring was just reaching Baffin Island in the Canadian Arctic, a famed local hunter took Nweeia out on the ice searching the open water for those tusk-bearing, high-Arctic whales. "I was sitting on a bucket out on the ice doing polar bear watch," he says. At that time of year, daylight lasts...

Twice each day at more than 1,100 sites around the world, scientists simultaneously loft weather balloons to collect data about Earth's atmosphere. During each balloon's ascent, which lasts a couple of hours or so, instruments garner information about air temperature, humidity, barometric pressure, wind speed, and wind direction. Meteorologists feed all of these data into their computer...